<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        #box1 {
            width: 200px;
            border: 1px solid black;
            overflow: hidden;
        }

        #box2 {
            width: 100px;
            height: 200px;
            background: red;
        }
    </style>
</head>
<body>
<!--
<div id="box1"></div>
<div id="box2"></div>
-->

<div id="box1">
    <div id="box2"></div>
</div>

</body>
</html>